GPT-4 → GPT-5
Migrate your prompts and tool calls from GPT-4 to GPT-5.
OpenAI released GPT-5 with meaningful changes to instruction-following and tool-call shapes. Most prompts work as-is, but tool descriptions tightened and the system-prompt influence shifted. Plan for one short audit pass before flipping production.
Prompt translation tips
- · Start with your existing system prompt unchanged and run a 20-prompt evaluation set side-by-side; only change what fails.
- · Watch for instruction-following drift — different labs follow instructions at different temperatures (Anthropic models are stricter).
- · Tool-call shapes vary — review parallel tool calls, JSON-only output requirements, and any structured-output hints you depend on.
- · If you use vision, retest your prompt set with the same images — different models excel at different layouts.
Pricing math
Moving from OpenAI: GPT-4.1 to OpenAI: GPT-5:
- Input tokens: –$0.75/Mtok (cheaper).
- Output tokens: +$2.00/Mtok (more expensive).
Capability gaps to plan for
- · Context window shrinks from 1048K to 400K — plan for chunked retrieval if you load whole documents.
- · Run your full eval suite against the new model in a Switchy Space before flipping production.
Side-by-side
See the full comparison: OpenAI: GPT-4.1 vs OpenAI: GPT-5.